1. Field of the Invention
The invention pertains to a process for the treatment or preparation of mixtures comprised of at least one light metal, particularly aluminum, or an alloy of the at least one metal and at least one nonmetallic phase, formed of at least one oxide or one oxide coupling of the at least one metal, if necessary, with at least one additional material, for example salt or salt mixtures, particularly slag or dross resulting from processes for the production, processing as well as reclamation of aluminum and aluminum alloys, at higher temperature for a subsequent independent or separate process for the recovery or separation of the metallic phase from the nonmetallic phase via, if necessary, at least partial separation of the constituents of the metallic phase.
In addition the invention pertains to an apparatus for the treatment or preparations of mixtures consisting of at least one light metal, particularly aluminum, or an alloy of the at least one metal and at least one nonmetallic phase, formed of at least one oxide of the at least on metal, if necessary, with at least one additional material, for example salt or salt mixtures, particularly slag or dross resulting from processes for the production, processing as well as reclamation of aluminum and aluminum alloys, at higher temperatures for a subsequent process for the recovery or separation of the metallic phase from the nonmetallic phase via an at least partial separation of the constituents of the nonmetallic phase, including essentially a container having at least one opening for charging the mixture and/or slag as well as, if necessary, additional materials, and for the discharge of the formed homogenized charge particularly for carrying out the process.
2. Discussion of the Background of the Invention and Material Information
During substantially all processes for the production, reclamation, processing and the like of light metals, particularly aluminum and aluminum alloys, large quantities of waste materials often result, such as for example, slag, dross, mixtures and the like, which in addition to the nonmetallic phase also contain metal, possibly at a high fraction. Light metals have, on one hand, a high affinity for oxygen and nitrogen and thus form strong high melting point oxides and nitrides, particularly during the use of technical melting and remelting processes when carried out in air, and on the other hand the difference in the specific weight between the metal phase and the nonmetallic phase or the reaction products is small. In connection with the interfacial tensions the previously noted chemical and physical properties of light metals, are the reason why a separation of the nonmetallic and the metallic phase, even when the latter is present in the mixture in liquid form, is difficult and not workable in the required scale. A reclamation of the metal, respectively a demetallization of the waste materials, appears however to be of great interest not only from the economic standpoint, but to an increasing extent ecological aspects and constantly more stringent environmental laws are becoming more important.
A large number of processes and devices for the phase separation or reclamation of metals from mixtures, such as slag and dross, have already been proposed and described. These are based substantially on that a coagulation of the finely dispersed metal or the fine droplets in the molten state should flow together into larger aggregates that can then be removed.
To that end it has become known that the stirring of the mixture causes a coagulation of the metallic particles. The stirring can therewith be the result of stirring means or can be practiced in a rotating container. European Patent Publication EP-A2-0322207, for example, teaches a process, in which in a rotating container, into which dross was charged in the cold state, is heated to a temperature above the melting point of the metal, with a plasma burner. The thereby agglomerated metal must then be removed through tapping holes in the drum wall and the substantially nonmetallic phase is scraped from the container wall with a tool. U.S. Pat. No. 4,997,476 and British Patent Publication GB-A-2 228 014 describe a further process wherein a container rotates about its vertical axis, which again is heated with a plasma burner, whereby, after extensive treatment times of the charged dross, a discharge of liquid metal is said to be possible. It was also attempted, as set forth in U.S. Pat. No. 4,575,056, to press out molten aluminum from hot dross. Centrifugal processes with essentially continuous and discontinuous procedures are also known. Such centrifugal processes and devices however have the inherent problem, that the differences in the specific weight of the metallic and nonmetallic phases is often quite small and that a centrifugal separation thus requires very specific working procedures.
All of the processes, developed to date, for the separation of the metallic phase of light metals from at least one nonmetallic phase containing these same light metals have the common disadvantage that separation or a demetallization is not accomplished in a sufficiently high extent, so that particularly the ecological problems of high deposit costs and the ecological recyclability of the residue remain largely unsolved.